I picked up several Pentax zooms to play with on my K-7. This one bested a Rikenon 35-135 and a Sakar 28-200 as well as another Kobori-Vivitar, the 28-85. (Kobori-made Vivitars use serial numbers that begin with '77'.) It weighs out at around 470g and takes 72mm filters - but I use a step-down ring to 67mm with no ill effects. Compared to the other zooms, the 28-105 shows greater contrast and very nice color, and somehow a bit more crispness on the preview screen which makes for better focusing. It isn't great for flare resistance but the others were worse. It also has 1:5ish "macro" abilities at the long end. For Pentax users it has the 'A' aperture setting, which means nothing to :43: cameras of course. Here are two samples of the neighbor's bird feeder - these were shot through our double-pane sliding door (it was Cold out ) and from RAW images processed in Elements 9. Feeder is about 25' from me, background about 50' away. I tried the other zooms out on my G1 as well, and results were the same as on the K-7: this lens is easily the best of my adapted zooms!